1. Field of the Invention
The present invention relates to a display apparatus having a display panel such as a plasma display panel of a matrix display system and to a displaying method regarding the display panel.
2. Description of the Related Arts
In a display apparatus using a display panel such as a plasma display panel, an average luminance level of an image signal is obtained and, when the average luminance level increases to a reference value or more, luminance is restricted. This is because it is intended to suppress electric power consumption of the display apparatus and prevent deterioration of the display panel which results from heat generation.
There is, however, a problem such that if the luminance restriction is performed by giving a priority to the prevention of the heat generation from the display panel, the luminance is restricted more than necessary, so that an image on the display panel becomes dark.
It is, therefore, an object of the present invention to provide display apparatus and method which can prevent heat generation from a display panel without unnecessarily reducing a luminance level.
According to the invention, there is provided a display apparatus comprising: an average luminance level detector for dividing a frame shown by an input image signal into a plurality of blocks and detecting an average luminance level of the image signal in each of the plurality of blocks; an adjacent block detector for detecting adjacent blocks having a relation such that a difference of the average luminance levels is equal to or larger than a predetermined level from the plurality of blocks in accordance with the average luminance level of each of the plurality of blocks detected by the average luminance level detector; a state continuation detector for detecting that the adjacent blocks detected by the adjacent block detector have continued the state where the difference of the average luminance levels is equal to or larger than the predetermined level for a predetermined time, to generate a luminance restriction command signal; and a display element for displaying an image corresponding to the image signal while restricting a luminance level of the image signal in response to the luminance restriction command signal.
According to the invention, there is provided a displaying method comprising the steps of: dividing a frame shown by an input image signal into a plurality of blocks and detecting an average luminance level of the image signal in each of the plurality of block; detecting adjacent blocks having a relation such that a difference of the average luminance levels is equal to or larger than a predetermined level from the plurality of blocks in accordance with the average luminance level of each of the plurality of blocks; detecting that the adjacent blocks have continued the state where the difference of the average luminance levels is equal to or larger than the predetermined level for a predetermined time, to generate a luminance restriction command signal; and displaying an image corresponding to the image signal while restricting a luminance level of the image signal in response to the luminance restriction command signal.